Nokea
Compared to naïve T cells, memory T cells:
- A. Take less time to become activated
- B. Have less need for costimulation during activation
- C. Have a much longer life span
- D. All of the above are correct
Correct Answer: D
Rationale: Memory T cells, compared to naïve T cells, take less time to become activated as they have previously encountered the antigen. They also have less need for costimulation during activation due to their enhanced sensitivity. Furthermore, memory T cells have a much longer life span, allowing for a more rapid and robust immune response upon re-exposure to the antigen. Therefore, all of the statements in choices A, B, and C are correct, making option D the correct answer.
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PNAd is expressed on
- A. HEV
- B. Lymphocytes
- C. Dendritic cells
- D. Thymus
Correct Answer: A
Rationale: The correct answer is A: HEV (High Endothelial Venules). PNAd is a ligand expressed on high endothelial venules, which helps in the recruitment of lymphocytes from the bloodstream into secondary lymphoid organs. PNAd is not primarily expressed on lymphocytes themselves (B) or dendritic cells (C). While PNAd can be involved in thymocyte migration to the thymus, it is not expressed on the thymus itself (D). Thus, the correct answer is A as it directly relates to the function and location of PNAd expression.
What is the medical term for excessive bleeding?
- A. Thrombosis
- B. Embolus
- C. Hemorrhage
- D. Hemostasis
Correct Answer: C
Rationale: The correct answer is C: Hemorrhage. Hemorrhage refers to excessive bleeding. Thrombosis (A) is the formation of blood clots, not excessive bleeding. Embolus (B) is a blood clot that travels through the bloodstream and blocks a blood vessel. Hemostasis (D) is the process of stopping bleeding, not the term for excessive bleeding. In summary, only choice C directly relates to the medical term for excessive bleeding.
Which patient is at risk for hypernatremia?
- A. Has a deficiency of aldosterone
- B. Has prolonged vomiting and diarrhea
- C. Receives excessive IV 5% dextrose solution
- D. Has impaired consciousness and decreased thirst sensitivity
Correct Answer: D
Rationale: Impaired consciousness leads to decreased thirst sensitivity, preventing adequate water intake and increasing sodium concentration in the blood.
How do regulatory T cells (Tregs) maintain immune homeostasis?
- A. By killing infected cells
- B. By producing pro-inflammatory cytokines
- C. By suppressing immune responses using IL-10
- D. By activating macrophages
Correct Answer: C
Rationale: Regulatory T cells (Tregs) maintain immune homeostasis by suppressing immune responses using IL-10. Tregs release IL-10, which inhibits the activity of effector T cells and other immune cells, preventing excessive immune responses and maintaining balance. This mechanism helps prevent autoimmune diseases and chronic inflammation. Choices A, B, and D are incorrect because Tregs do not kill infected cells, produce pro-inflammatory cytokines, or activate macrophages. Instead, Tregs focus on regulating and dampening immune responses to maintain overall immune balance.
The major role of the complement system is to work in conjunction with
- A. antibodies to lyse cells via the C8 and C9 components
- B. the major histocompatibility complex for cell recognition
- C. antibodies to opsonize cells
- D. the T-cell receptor for production of lymphokines
Correct Answer: A
Rationale: Rationale: The complement system is a group of proteins that enhance the ability of antibodies and phagocytic cells to clear pathogens. Choice A is correct because the C8 and C9 components of the complement system form the membrane attack complex which lyses cells. Choices B, C, and D are incorrect because the complement system primarily functions independently of the major histocompatibility complex, antibodies for opsonization, and T-cell receptor for lymphokine production.